Control system.



-K. A. SIMMON & A. J. HALL.

CONTROL SYSTEM.

APPLICATIONAFILED JULY 24.1914.

1,236,780. Patented Aug. 14,1917.

WITNESSES: INVENTOR Kar/ A. 5/mm0n 5r Arfhu/J. Ha//.

BY M ATTORN EY v UNITED STATES PATENT OFFICE.

' KARL A. SIMMON, 0F EDGEWOOD PARK, AND ARTHUR J. HALL, OF WILKINSBURG,

PENNSYLVANIA, ASSIGNORS TO WESTINGHOUSE ELECTRIC AND MANUFACTURINGCOMPANY, A CORPORATION OF PENNSYLVANIA.

CONTROL SYSTEM.

Specification of Letters Patent.

Patented Au". 14, 1917.

Application filed July 24, 1914. Serial No. 852,826.

To all whom it may concern:

Be it known that we, KARL A SIMMON, a citizen of the United States, anda resident of Edgewood Park, in the county of Allegheny and State ofPennsylvania, and An- THUR J. HALL, a subject of the King of GreatBritain, and a resident of Wilkinsburg, in the county of Allegheny andState of Pennsylvania, have invented a new and useful Improvement inControl Systems, of which the following is a specification.

()ur invention relates to control systems for dynamo-electric machinesthat are employed t'or propelling electric locomotives or other electricvehicles, and it has special reference to the regulation of polyphaseinduction motors that are utilized for driving common load.

One of the objects of our invention is to provide a system forcontrolling the driving units or motors of an electric locomotive ortrain of electric vehicles in such manner that a predetermined divisionof the load between. the driving units shall be maintained at all times,irrespective of variations in mechanical construction and electricalcharacteristics of the motors, the construction and operation of thegoverning devices, or differences-in the diameters of driving wheels.

In another aspect, it is the object, of our invention to provideautomatic means for proportioning the total load between a plurality ofmotor driven units which may constitute a plurality of separatemotor-driven axles, motordriven trucks or locomotive half units.

More specifically,it is the object of our invention to provide a controlsystem having simple connections for automatically regulating thedistribution of load between several polyphase inductiondrivingmotorsthat are governed by electro-pneumatically operated liquid rheostats bymeans of a three-position differential or. balancing relay which isresponsive to relative load conditions upon the driving motors and whichcooperates with the operating mechanisms in such manner as to decreasethe load of the overloaded motor or motors, and concurrently increasethe load carried by the remaining motor or mo tors under conditions ofunbalanced loads.

For the sake of simplicity, we shall set forth our invention asembodying a control system of the multiple unit type for governmg theoperation of a pair of polyphase induction motors through the agency ofsepa rate electrically controlled liquid rheostats, the several motorsbeing mounted upon the respective driving trucks of a single locomotive,although it is evident that each truck may be provided with a pair ofdriving motors, the loads of which may be balanced, or that two halfunits of a locomotive may be similarly regulated.

In the accompanying drawing, Figure 1 is a view in side elevation of alocomotive having driving motors that may be conveniently controlled bya system embodying our invention; and Fig. 2 is a diagrammatic view ofour control system as applied to the motors of the locomotive shown inFig. 1.

Referring to the drawing, a plurality of supply circuit conductors 1 areadapted to deliver polyphase alternating current energy to primarywindings P1 and P2 of a pair of driving motors M1 and M2 that areconnected in multiple relation and which embody secondary windings S1and S2 that are respectively connected to liquid rheostats LR]. and LE2.Themotors M1 and M2. are mounted upon driving trucks 2 and 3 that areassociated with andcarry a locomotive cab or body 5 in a wellknownmanner.

The several rheostats LRl and LR2 are of like constructionand eachembodies a regulating valve 7 that is adapted to be raised and loweredin position to determine the height of the electrolyte in which aplurality of electrodes 8 are adapted to be immersed.

The several regulating valves 7 of the respective rheostats LRl and LE2are adapted to be actuated by means of electrically controlled pneumaticoperating devices ODl and OD2, respectively, each of said devicescomprising a cylinder 10, a movable piston 11, an electricallycontrolled valve oif1, (the numeral designating the rheostat withwhich'the valve is associated) that is located at the u per end of thecylinder 10 and is normal y open to admit a suitable operating fluid,and another electrically operated valve on-1 that is arranged to controlthe admission of operating fluid to the lower end of the cylinder 10 andwhich is normally closed to the supply ofoperating fluid and opened tothe atmosphere.

The structural details of the several liquid rheostats and the operatingdevices are old in the art and their mode of operation is well known,inasmuch as devices of this type are fully set forth in our co-pendingapplication, Serial No. 846,289, filed June 20, 1914. It will beunderstood that when both valves are deenergized, unbalanced pressuresact upon the pistons 11 to elfect downward movements thereof, when bothvalves are energized, unbalanced pressures serve to move the pistons inan upward direction, and when only the on-1 magnet valves are energized,the pistons are held stationary.

The normal manually .controlled operation of the system is governed bymeans of a master controller MC which comprises a plurality ofstationary contact terminals 13+, 12, 13, and 14 which are adapted tocooperatively engage a movable conducting segment 15 upon theposition-indicating lines marked Lower, Hold andBaise. The severalcontact terminals 12, 13 and 14 are respectively connected to apluralityof train line conductors 12', 13 and 14, while the positive side of anauxiliary battery B is connected to terminal 13+ and its negative sideto a train line conductor B.

The several train line conductors 12, 13', 14 and B- are so connected tothe several off and on magnet valves of the operating devices, ODl andCD2 that, under normal'operating conditions, said devices actuate therespective regulating valves 7 of the rheostats LRl and LE2 in an upwarddirection when the master controller MC occupies its raise position,said regulating valves are held stationary when the master controller MOis in its hold position, and said valves are moved downwardly by theirrespective operating devices when contact terminals B+ and 12' onlyengage the conducting segment 15 in the lower position of the mastercontroller. The line switch LS is held closed by its closing magnet 16when ever the master controller MO is in any of its operative positions.For a further exposition. of the control apparatus and the functionsthereof, reference may be had to the co-pending application to whichattention has been directed.

In order to provide for a predetermined division of the load between theseveral driving motors M1 and M2, an auxiliary differential or balancingrelay BB is provided, which comprises a plurality of mechanicallyassociated magnetizable cores 20 and 21 that are respectively providedwith series current coils 22 and 23 and voltage coils 24'and 25. Theseries current coils 22 and 23 are, respectively, connected in seriescircuit with motor lead conductors 22 and 23 associated with the severalmotors M1 and M2, while the voltage coils 24 and 25 are connected to beinfluenced by tlie voltages of the respective motors. The strengths ofthe opposing electro-magnets or relays are, therefore, dependent uponthe loads upon the motors M1 and M2. Under normal operating conditions,when the driving motors M1 and M2 are carrying their proper shares ofthe total load, the cooperating balancing relays just neutralize eachother and no resultant movement thereof is effected. However, if eitherof the driving motors carries more that its intended share of the load,one of the relays overcomes the other and a movement thereof in onedirection or the other results.

The several cores 20 and 21 are rigidly associated with a supporting rod28 that has sliding bearings in a plurality of bearing members 29, 30and 31, and the respective ends of the rod 28 are provided with aplurality of sets 33 and 34 of spring-supported movable switch members35-, 36 and 37, and 38 39 and 40, the several switch members beingnormally adapted to make cooperative engagement with stationary contactterminals 35, 36*, 37, 38 39, and 40*. Moreover, switch members 37 and38 are provided with another set of stationary contact terminals 37 and38 with which engagement is effected when the associated relays areactuated in a predetermined direction. The switch members 35, 36, 39 and40 are resiliently supported by coil springs 43, one end of each ofwhich is pinned or otherwis secured to the rod 28 and the other endthereof engages the switch member. The switch members 37 and 38 areresiliently positioned by a plurality of springs 43 between which saidswitch members are disposed.

The set 33 of auxiliary switches is adapted to control the energizingcircuits of the magnet valves off-1 and on1 of rheostat LRl, while theset 34 of auxiliary switches similarly governs the circuit connectionsof the magnet valves off2 and 0n 2 of rheostat LE2. The balancing relayBR is adapted to occupy three positions, it being normally maintained inits neutral or middle position, as shown in Fig. 1, by means ofcentralizing springs 45 and 46 which are respectively disposed aroundthe rod 28 and between the bearing member 30 and the cores 20 and 21.

Assuming the arrangement of apparatus and circuit connections to be asshown, the operation thereof is as follows: The master controller MO isfirst moved into its raise position thereby completing a circuit fromterminal B+ which includes conducting segment 15, terminal 14, and trainline conductor 14: where the circuit divides, one branch includingcooperating contact members 37 and 37, coijperating contact members 36and 36, and energizing coil of magnet valve ofi'-1 to the B train lineconductor, while the other branch includes coiiperating contact members38 and 38, coiiperating contact members 39 and 39 and energizing coil ofmagnet valve ofl2 to the conductor B. Concurrently, another circuit isestablished from contact terminals 13-}- which includes contact segment15, contact terminal 13, and train line conductor 13 where the circuitdivides, one branch traversing cooperating contact members 35 and 35 andenergizing coil of magnet valve on-1 to the B conductor, and the otherbranch traversing cooperating contact members to and 40 energizing coilof magnet valve on2 and thence to the train line conductor B. At thesame time that these circuits are completed another circuit is alsoestablished from contact terminal 13+ through conducting segment 15,contact terminal 12, train line conductor '12, and energizing coil ofclosing magnet 16 of the line switch LS to the B train line conductor.

Having established the circuits just traced, the line switch LS isclosed to connect the multiple related motors M1 and M2 to the supplycircuit conductors 1, while all of the off and on magnet valves areenergized and correspondingly actuated, the on magnet valves beingopened to admit operating fluid below the pistons 11 and the off magnetvalves being closed to the supply of operating fluid and open the upperends of the cylinders 10 to the atmosphere. Thus, operating fluid isreleased from the upper ends of the cylinders 10, whereby unbalancedpressure conditions are eflected which result in upward movements of theseveral pistons 11 and their associated regulating valves 7. When theregulating valves 7 are gradually raised in position, the continuouslyinflowing electrolyte within the rheostats LR1 and LR2 iscorrespondingly raised in level, and, consequently, resistance isgradually excluded from the motor secondary circuits, thereby causingthe motors M1 and M2 to be accelerated.

Thus,.concurrent operation of the several operating devices ODl and OD2is effected, provided the load is properly divided between the severaldriving motors M1 and M2. For purposes of explanation, however, it willbe assumed that for some reason, possibly because of differences inwheel diameters, motor M1 has a tendency to carry more than its intendedshare of the load. The coils 22 and 24 of the balancing relay BR,therefore, produce a magnetic pull in excess of that resulting from theaction of the coils 23 and 25 of the opposite relay and, therefore, thecores 20 and 21 and their associated supporting rod 28 are actuated tothe left. In so doing, engagement between switch members 35, 36 and 38and their cooperating terminals 35*, 36 and 38* is maintained, whileswitch members 37 39 and 10 are caused to disengage their cooperatingterminals 37, 39 and 40*, the switch member 37 being brought intoengagement with its other set of terminals 37 As the switch member 37disengages its terminals 37, the main energizing circuit from contactterminal 14 of the master controller MC is interrupted. However, anenergizing circuit is immediately reestablished from terminal 13 by theengagement of switch member 37 with cooperating terminals 37 so that themagnet valves ofl l and onl continue to be energized as before.Therefore, the operation of rheostats LE1 and its associated motor M1continues without interruption. However, the disengagement of switchmembers 39 and 40 from their cooperating terminals 39 and 40 serves tointerrupt the energizing circuits of magnet valves ofi2 and on-2, andsaid magnet valves are de'e'nergized and are returned to their initialpositions to admit operating fluid above the piston 11 of device ()D2and to release it from beneath said piston, whereby said iston and itsassociated regulating valve is moved downwardly to lower the level ofthe electrolyte within rheostat LE2 and to correspondingly decrease thespeed of motor M2. It is, therefore, manifest that motor M1 continues toincrease its speed and load, while motor M2 concurrently reduces theload which it carries until an equalization of loads between the severalmotors is effected, or at least, until the desired division of loadobtains.

Without further description, those skilled in the art will understandthat similar changes in circuit connections and in the operation of theapparatus are effected if the load upon motor M2 exceeds that car riedby motor M1.

In certain instances, it ma be desirable to make the automatic operationof the balancing relay dependent upon the relative motor currents alone,which may readily be accomplished by omitting the voltage coils of theopposing relays. Moreover, by simple rearrangements of the controlcircuits with respect to the balancing relay, provision may be made formerely interrupting the circuit of the off magnet valves associated withthe rheostat which controls the motor having the greatest load, wherebyits load is held substantially constant until the other driving motorincreases sufliciently in speed to effect the desired proportioningthereof.

Obviously, these and other modifications in circuit connections as wellas in the structural details of the apparatus may be effected withoutdeparting from the spirit and scope of our invention, and we desire thatonly such limitations shall be imposed as are indicated in the appendedclaims.

We claim as our invention:

1. In a control system, the combination with a plurality of electricdriving units working upon a common load, of electroresponsive means fordividing the load between said units and embodying opposingelectromagnets and a plurality of sets of switches associated therewithfor severally modifying the operation of said units.

2. In a control system, the combination with a plurality of electricmotors working upon a common load, and means for individually controllinthe operation thereof, of a dlfferential re ay having coils respectivelyassociated with said motors, and a. plurality of sets of switchesoperatively associated therewith and severally adapted to affect theoperation of said controlling means.

3. In a control system, the combination with a plurality of electricmotors working upon a common load, and means for individuallycontrolling the operation thereof, of a differential relay having coilsrespectively associated with said motors and a plurality of sets ofswitches operatively as sociated therewith for modifyin the o eration ofone or the other of sai contrdlling means in accordance with the actionof said differential relay.

4. Ina control system, the combination with a plurality of electricmotors working upon a common load, and means for individuallycontrolling the operation thereof, of opposing electromagnets severallyinfluenced by circuit conditions of the respective motors, and switchesoperated thereby for modifying the operation of said controlling meansin accordance with predetermined conditions.

5. In a control system, the combination with a plurality of motorsworking upon a common load, and a plurality of electrically controlleddevices for separately governing said motors, of a differential relayhaving a plurality of coils respectively influenced by load conditionsof the several motors and a plurality of sets of switches operatedthereby and respectively adapted to govern the operation of saidelectrically controlled motor-governing devices, each set of switchesbeing adapted to modify the action of its associated governing deviceswhen actuated in one direction and to maintain normal operation thereofwhen actuated in the opposite direction.

6. In a control system, the combination with a plurality of motors.working upon a common load, and a plurality of electrically controlleddevices for separately governing said motors, of a differential relayhaving a plurality of coils respectively influenced by the loads uponthe several motors and normally biased to a neutral position, and aplurality of switches associated therewith and'adapted to cooperativelyengage their respective terminals when said relay occupies its neutralposition, part of said switches being adapted to disengage theirterminals when actuated in one direction and to maintain engagementtherewith when actuated in the other direction.

7. A differential relay adapted to occupy three positions and comprisinga pair of associated opposing electromagnets, a plurality of sets ofstationary contact terminals and a plurality of movable contact membersadapted to cooperatively engage a portion of said sets of terminalsunder normal conditions, and to maintain engagement'with certain of saidsets of terminals and to effect disengagement of other of said sets ofterminals when actuated in one direction and vice-versa.

8. A diflerential relay adapted to occupy three positions and biased toits middle position and embodying a plurality of spring supportedmovable contact members and cooperating stationary contact terminals, aportion of saidcontact members and terminals being adapted forcooperative engagement in the neutral and in one other position thereof,and another portion of said members and terminals being adapted forcooperative engagement in the neutral and in the remaining positionthereof.

9. In a control system the combination with a plurality of motorsworking upon a common load, and a plurality of electrically controlleddevices for separately governing the operation thereof, of a pair ofassosociated opposing relays severally responsive to load conditions ofsaid motors and adapted to occupy three operating positions, beingnormally biased to. a middle position, and a plurality of sets ofswitches for severally controlling the action of said governing devicesand adapted to be actuated by said relays in accordance with therelative load conditions of said motors.

10. In a control system the combination with a plurality ofmotorsworking upon a common load, and a plurality of electricallycontrolled devices for separately governing the operation thereof, of athree-position differential relay having a plurality of coils responsiveto the load conditions of the respective motors and normally biased toits middle position, and a plurality of sets of switches associatedtherewith and actuated thereby for severally controlling the operationof said governing devices in accordance with relative load conditionsupon said motors.

11. In a control system, the combination with a plurality of electricdriving units working upon a common load, of electroresponsive meansembodying a plurality of sets of current and potential coils, said setsof coils being respectively dependent upon the power load conditions ofthe respective driving units, and switching means operated by saidelectro-responsive means,

whereby the operation of said driving units is governed.

12. In a control system, the combination with a plurality of electricdriving units working upon a common load, of a difierential relay havinga current coil and a potential coil responsive to circuit conditions ofone of said driving units, and a current coil and a potential coilresponsive to circuit conditions of the other of said driving units, andswitching apparatus associated with said relay, whereby the operation ofsaid driving units is governed and the relative loads thereof areproportioned accordingly.

In testimony whereof, we have hereunto sulis'cribed our names this 6thday of July, 19 4.

KARL A. SIMMON. ARTHUR J. HALL.

